Class X Sciences
[papers from previous years]
State the reason why carbon can neither form
C4+ cations nor
C4− anions but forms covalent compound.
Also state the reason to explain why covalent compounds:
(i) are bad conductors of electricity.
(ii) have low melting and boiling points.
Answers
The valancy of carbon is 4 it has to gain or donate 4 electrons to get stable . it cannot gain four electron as carbon atom having 6 protons is very small to handle 10 electron and it cannot donate electrons as it needs a lot of energy to do so , that's why it forms covalent bonds .
1) generally covalent bonds have free electrons present in them so electricity can be transferred
2)covalent bonds have weak bond present in them so they have low melting and boiling point
♤ Carbon can't lose 4 electron to form C^4+ ions as very high energy is required to remove 4 electrons.
♤ Carbon can not gain 4 electron to form C^4- ions as 6 protons can not hold 10 electrons and Energy needs to be supplied to overcome repulsion.
♤ Carbon can share 4 electron to form covalent compounds.
♤ Carbons do not conduct electricity as they are non - polar and do not form ions.
♤ They have low melting points and boiling points due to weak van der Waal's force of attraction between molecules